Active North Atlantic deepwater formation during Heinrich Stadial 1

ZHAO, NING; MUGLIA, JUAN; CARTAPANIS, OLIVIER; HAUG, GERALD H.; RAND, DEVIN; MULITZA, STEFAN; BAUCH, HENNING A.; REPSCHLÄGER, JANNE; LISIECKI, LORRAINE; SCHMITTNER, ANDREAS; SCHIEBEL, RALF

QUATERNARY SCIENCE REVIEWS

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2021 vol. 270

0277-3791

Deepwater circulation significantly changed during the last deglaciation from a shallow to a deep-reaching overturning cell. This change went along with a drawdown of isotopically light waters into the abyss and a deep ocean warming that changed deep ocean stratification from a salinity-to a temperature-controlled mode. Yet, the exact mechanisms causing these changes are still unknown. Furthermore, the long-standing idea of a complete shutdown of North Atlantic deepwater formationduring Heinrich Stadial 1 (HS1) (17.5e14.6 kyr BP) remains prevalent. Here, we present a new compilation of benthic d 13 C and d 18 O data from the North Atlantic at high temporal resolution with consistent age models, established as part of the international PAGES working group OC3, to investigate deepwater properties in the North Atlantic. The extensive compilation, which includes 105 sediment cores, reveals different water masses during HS1. A water mass with heavy d 13 C and d 18 O signature occupies the Iceland Basin, whereas between 20 and 50º N, a distinct tongue of d18O depleted, d13C enriched water reaches down to 4000 m water depths. The heavy d13C signature indicates active deepwater formation in the North Atlantic during HS1. Differences in its d 18 O signature indicate either different sources or an alteration of the deepwater on its southward pathway. Based on these results, we discuss concepts of deepwater formation in the North Atlantic that help to explain the deglacial change from a salinity-driven to a temperature-driven circulation mode.